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use std::mem::MaybeUninit;
pub trait ChunkIter<T, I: Iterator<Item = T>> {
fn chunks<const N: usize>(self) -> Chunks<T, I, N>;
}
impl<T, I> ChunkIter<T, I> for I
where
I: Iterator<Item = T>,
{
fn chunks<const N: usize>(self) -> Chunks<T, I, N> {
Chunks {
buffer: unsafe { MaybeUninit::uninit().assume_init() },
iterator: self,
needs_dropping: 0,
}
}
}
pub struct Chunks<T, I: Iterator<Item = T>, const N: usize> {
buffer: [MaybeUninit<T>; N],
iterator: I,
needs_dropping: usize,
}
impl<T, I: Iterator<Item = T>, const N: usize> Iterator for Chunks<T, I, N> {
type Item = [T; N];
fn next(&mut self) -> Option<Self::Item> {
for x in &mut self.buffer {
*x = MaybeUninit::new(self.iterator.next()?);
self.needs_dropping += 1;
}
self.needs_dropping = 0;
unsafe { Some(std::mem::transmute_copy(&self.buffer)) }
}
}
impl<T, I: Iterator<Item = T>, const N: usize> Drop for Chunks<T, I, N> {
fn drop(&mut self) {
for x in 0..self.needs_dropping {
let _ = unsafe { self.buffer[x].as_ptr().read() };
}
}
}